1. Field of the Invention
This invention relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The invention also relates to trip actuator assemblies for circuit breakers.
2. Background Information
Electrical switching apparatus include, for example, circuit switching devices; circuit interrupters, such as circuit breakers; network protectors; contactors; motor starters; motor controllers; and other load controllers. Electrical switching apparatus such as circuit interrupters and, in particular, circuit breakers of the molded case variety, are well known in the art. See, for example, U.S. Pat. No. 5,341,191.
Circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. Molded case circuit breakers typically include a pair of separable contacts per phase. The separable contacts may be operated either manually by way of a handle disposed on the outside of the case or automatically in response to an overcurrent condition. Typically, such circuit breakers include an operating mechanism, which is designed to rapidly open and close the separable contacts, a trip unit, which senses overcurrent conditions in an automatic mode of operation, and a trip actuator assembly, which in response to such overcurrent conditions, is actuated by the trip unit to move the operating mechanism to a trip state, thereby moving the separable contacts to their open position. See, for example, U.S. Pat. Nos. 5,910,760; and 6,144,271.
It is sometimes desirable to integrate a new trip unit feature or a new or different type of trip unit into a circuit breaker. For example, it is sometimes desirable to integrate an electronic trip mechanism (e.g., without limitation, a flux shunt trip actuator) into the trip actuator assembly. Whether this is done during the assembly of a new circuit breaker or as a retrofit of an existing circuit breaker, it typically requires that numerous components be fit within the circuit breaker housing, where space is limited. Effectively arranging the trip actuator assembly within the circuit breaker housing such that it works well, yet does not require relatively significant modifications or alterations to the housing or to the circuit breaker in general, is a challenging endeavor.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in trip actuator assemblies therefor.